The most forceful meteorological blocking of the 20th
Century, if not during the last 150 years or longer, was established at
the onset of the Second World War in autumn 1939. The subject was never
recognised scientifically. On the other hand recent atmospheric blocking
events received much attention. Why was the winter 2009/2010 unexpectedly
the coldest winter for 30 years? Why was
Russia
caught in a heat wave in summer 2010? And why had the global mean
temperature for December 2010 actually been below the previous 30-year
mean? Many questions, for which
more convincing answers would be available, if science had been more
conscientious about what had happened at the onset of WWII, namely, what
had caused the blocking of usual weather patterns in autumn 1939, and
whether that had anything to do with naval war activities in the seas off
European coast lines.

The
'west wind zone', or west-wind -drift (WWD) as the German weather service
used to call it, is defined as the atmospheric circulation of air in the
mid-latitudes of the earth (about 40 degrees and 60 degrees), which may
extend up to the latitude of 70 degrees. As part of the planetary
circulation, it always runs from west to east. Any disorders in the
circulation causes severe undulations, i.e. the flow has deflections from
north or south. At high altitudes (10-15 km) the air circulation is called
"jet stream" that can achieve a speed of 500 km per hour. Up to
WWII little was known about the "jet stream", while the general
circulation was summarized in meteorology as: The Westerlies. How did a
disturbance of circulation come about in 1939? This will be discussed
below.

.

Fig. C5-1

Fig. C5-2

Fig. C5-3

b. The first days and the cyclone in the German Bight

The weather was fine when the Deutsche Luftwaffe and Wehrmacht
(German Air Force and Army) had begun the invasion of Poland at its
western borders at 04:48 local time on September 1st, 1939,
while the first naval gunfire of World War II came from the old German
battleship “Schleswig Holstein” which bombarded the Polish military
transit depot at Westernplatte in the Free City of Danzig on the Baltic.

Nothing
exceptional was expected from anyone at the weather forecast front. The
weather during the first few war days indicated a tendency toward
continental conditions, known as Indian summer. The daily weather analysis
of the ‘Seewarte’, the military weather service, mentioned this for
example:

·September 01, 1939: Over Central
Europe (CE) air pressure increases.

·September02, 1939: Modest pressure changes
in CE. The general weather situation is determined by an
extensive Low pressure system over the North Atlantic and a High over
Northern Scandinavia
.

·September 03, 1939: In the east of
the Scandinavian High, polar cold air is pushed toward
Germany
.

·September 05, 1939: The center of
the European Highs has moved further south-eastwards.

The usual flow of circulation may have been affected by numerous
war activities. I want to discuss only one example, which links naval
activities to the movement of a cyclone, and is one aspect that eventually
contributed to atmospheric blocking of the jet stream over
Europe
. The story lasted from September 10th to 13th, and
could be entitled: Cyclone attracted by naval warfare activities in the
Helgoland Bight (German Bight).

aa. Naval Activities:

Fig. C5-4

Fig. C5-5

A huge number of the Kriegsmarine vessels were stationed in the
North Sea
from day zero, and were highly active. The Royal Navy and Air Force showed
up several times around the
island
of
Helgoland
and the German coast with submarine, bomber and sea mine laying missions.
The German Navy was particularly engaged in planting contact mines from
Holland
’s coastal waters (off Terschelling) northwards across the German Bight
up to the entrance of the Skagerrak, at a distance of between 50 and 100
km off the coast of Schleswig-Holstein and
Denmark
, called the “Westwall”. The most north-westerly point announced by
the Germans as ‘Dangerous zone’ was the position: 56° 30’ North and
4° 25’ East. That was about half the distance between Skagerrak and
Scotland
. The first minefield locations were off Terschelling,
Esbjerg
, near Helgoland and two places off
Jutland
. (NYT, September 5,1939) As many as 300 mines an hour could be laid by
one single minelayer. (NYT, February 18, 1940), and the German Navy had
presumably several dozens in service to plaster the North Sea off the
German coast with ten-thousand sea mines.

bb. Cyclone attracted:

In the north of
Scotland
a low arrived on September 10th, presumably bound to travel via
Skagerrak
eastwards to the Baltic and beyond. It almost did, but before entering the
Skagerrak it swung southwards and moved straight to the center of naval
activities, and further along
Holland
to the
Belgium
coast on September 13th, as shown in Fig. C5-4. And again just
two days later on the 15th, at
8 a.m.
, there was a small low-pressure center (1005 mb) north of
Helgoland
(not shown) close to the location of meanwhile already large sea mine
fields.

Temperature map 6 (TM6), Fig. C5-6.

cc. The apparent correlation:

During September 1939 the sea water temperature decreased at the
station of
Helgoland
which is so unusual that one has to take notice, Fig.C5-5. First there is
an increase of one degree, then a drop of three degrees below average in
September. A higherfigure for a
corresponding period as inSeptember
1939 had only once before
been recorded, i.e. in September1875. The steep rise and drop in September 1939 has something
to do with extensive naval ship movements and military activities thattook place, ‘shovelling’ lower and warmer water up to the
surface. Once warmer water reached the surface, evaporation increased and
subsequently seawater cooled more quickly. It is as simple as that, and in
this case it can obviously be demonstrated.

It is also the explanation why the cyclone movement from September
10th to 13th chose a path via the German Bight,
which actually contributed to more continental conditions, by taking the
heat out of the
North Sea
too early. On this occasion it was only a very small proportion, but many
thousand further events over the next months eventually established the
blocking.

c. Blocking observed but not understood

It
lasted from mid September, until the first week of December, for
atmospheric blocking to fully establish itself, when severe cold flooded
all of Europe (see below, NZZ), and did not loosen its tight grip over the
entire winter season. The Seewarte recognised early that something strange
was going on, but had no idea of what the consequences were, and that it
all had something to do with the naval activities in the
North Sea
and Baltic. Here are a few excerpt statements from the daily analysis:

·September 19, 1939; Cyclonic
activity over the
Polar
Sea
area is high. The west-drift in the North will susequently move more and
more towards the South.

·September 23, 1939; with the
advance of Atlantic air into Central Europe a more forceful cyclone can
develop along this channel, which could extend its influence in
Central Europe
later.

·September 29, 1939; General weather
situation towards the end of the month clearly reveals changes indicating
the end of the Indian summer spell which leads to a time of increased
cyclone activity in
Europe
. In the weather chart this is indicated by a decline of the
Northwest-European high–pressure area (anticyclone), which dominated the
general weather for a long time. This high, that usually is located far to
the East (cf. the weather situation a year earlier) is responsible for the
well-known late summer period of fine weather, now pushed so far to the
West that Germany lies at its Eastern rim and thus got into the cold
Northern stream which was interspersed with disturbances.

·October 13, 1939; Along with a
peripheral low, the first effective gust of maritime air has reached
Northern Germany
. A continuous WWD (Westerlies), however, cannot be expected yet.

·October 19, 1939; A broad
high-pressure bridge has formed between the
Atlantic
and Scandinavian high.

·October 23, 1939; usual weather is
changing now and the high-pressure bridge which links the
Azores
high with the West Russian high is broken up. A transition to a west wind
situation is on the verge in German seas.

·October 28, 1939; since a high
pressure bridge from Middle Scandinavia to
Scotland
remains stationary, a further stream of cold air from the
Nordic
Sea
area is cut off.

·November 5, 1939: It now appears
that – like in many earlier years – a WWD with lively cyclone
activities will begin to move over
Europe
around the middle of the month.

·November 14, 1939; it seems that a
mainly sectional circulation is going to take over in the general weather
situation: its pressure field will be characterized by a long
high-pressure zone – Azores –Southern Germany –
Southern Russia
– and WWD-like turbulence activity north of these regions.

·November 29, 1939; A West Siberian
High is slowly retreating towards the East thereby allowing the
disturbance coming from the West to penetrate even deeper into the regions
of European Russia.

Fig.
C5-7

·November 30, 1939; a very distinct
west wind weather situation rules over North and
Central Europe
.

·December 1, 1939: The quite
distinct Atlantic frontal zone of the last few days is disintegrating.

Significant for all comments is that they talk about: ‘could,
should, or would’, but a case of normal Westerlies (west-wind-drift)
never materialized for long, as the two days from 29/11 to 01/12 show. Although
a highly interesting bit of information, the matter is still not discussed
in scientific literature, although it could have contributed significantly
to the study of "blocking mechanism". In summary the
expectations of the weather analyst for ‘lively cyclone activities’
did not materialize itself. Seawater temperature changes by devastating
war machinery were not imaginable to weathermen at that time.

It
remains to mention the fine analysis by the Neue Zürcher Zeitung (NZZ,
January 14, 1940) on the development of cold conditions in
Europe
after only three months into the war:

„Severe
cold which flooded the whole of
Europe
in the course of this week was by no means an accidental phenomenon that
set in surprisingly. It rather constitutes the peak of a development which
had its beginning in the first week of December. Towards its end high
pressure began to stabilize in North and Middle Europe, keeping away the
low Atlantic cyclones from the continent and diverting them mainly through
Greenland and Iceland waters to the Sea….As soon as occasional Atlantic
depressions moved East through the North Sea and Baltic, they were
immediately replaced by the entry of cold air from the Greenland area.”

What
the analyst missed is the fact that the blocking of the Westerlies (WWD)
started already in September, while the development since the first week
of December’ is not the beginning, but nearly the end of the blocking
process.

d.Not
competent enough to read the wind?

At the end of October 1939 the Seewarte analysts had realised that
the wind pattern over
Northern Europe
had changed completely, but lacked the competence to read the signs.
According to their observations:

·Hamburg reported
winds from the North-Eastern quadrant on almost two thirds of the dates
observed (33% easterly winds out of 65%) while North-Eastern winds
accounted only for a quarter (26%) of several previous years’ averages.
Otherwise the most frequent direction of the wind – South-West (24%) –
accounted for 9% of all cases. Thus the observations at this station alone
show what the weather charts of an extensive area will obviously indicate
as well (Seewarte, Nov. 02, 1939), next Figure C5-8.

This
is a very strong and clear indication that huge air masses moved towards
the
North Sea
, due to unusually high evaporation in all sea areas affected by naval
war. While the water of the seas was ‘stirred and turned’ the
‘steam’ rose upwards into the sky, causing an air inflow from easterly
directions, which subsequently prevented low-pressure systems to travel
along the west-wind-drift channel via North Sea and Central Europe into
the eastern hemisphere.

Fig. C5-8

Fig. C5-9

e. The whole winter season affected

The foregoing investigation stressed the significance of the
observed change of wind direction in
Hamburg
during October 1939. Wind direction had dramatically changed from
prevailing SW winds to dominating NE winds.

Even
more significant is the already mentioned research by A.J. Drummond (1943) that
the prevailing wind directions in South-West
England
(Kew Observatory near
London
) had changed dramatically. During the 155 winters from 1788 to 1942 only
21 had easterly winds whereby the three winters 1814, 1841, and 1940 the
wind came from NE to ENE, meaning more northerly than East. Another small
number of winters since 1841 (1845, 1870, 1879, 1891, 1895, 1904, 1929)
had prevailing SSE to ESE winds, Fig. C5-9. With the exception of the
winters 1801 and 1804 all of these 21 winters with predominant easterly
winds had a temperature below average (40.1°F; 4.5°C). While eleven of
the above winters had means between 34°F and 36°F, only few years with
westerly wind had means lower than 37°F (2.8°C), these being 1820, 1830,
1847, 1855 and 1886. That was pure blocking, but there is no sign that
science has paid any attention to this important observation.

f. How R. Scherhag
rated December 1939

In
his study on the "circulation disorders in 1940" R. Scherhag (1951) begins with December 1939, without taking into
account any of the numerous signs that could have been identified since
the war commenced. To him, December 1939 is still largely 'normal', which
he expresses as follows:

·__In
December 1939 there was already the beginning of a pressure increase over
the Greenland area, a slowdown of cyclones in the Iceland area, but an
increase of pressure over the Azores and Mediterranean. On the other hand,
since both, the Aleutian low pressure intensified and the air pressure
over northern
Siberia
was also significantly reduced, the picture is about an average
circulation.

Fig. C5-10

·__December
1939 shows over Russia a pronounced positive deviation instead of a
negative anomaly, as evidenced by the weakening of the Azores high,
combined with significant excess pressure over Greenland, which can be
regarded as typical at the beginning of an extremely cold winter.
Particularly, the additional northerly flow component over Northern Europe
is practically a shift of the cold pole in the direction of
Europe
, and thus a major cause for the formation of the extreme conditions in
January and February 1940.

R. Scherhag
admits:

"The ultimate cause why the
entire polar region was covered by an extremely high air pressure to such
an extent in January 1940 is still unknown to us”
(R. Scherhag, 1951)

Althoughtheremark was made60
years ago, the secret has not yet beenliftedby science, so thecause
isstillhiddento
us.

g. Ananthropogeniccontribution
to the preparationof a recordwinter

Both temporal and spatialcontext ofthe
waractivitiesare
unmistakable.This
could beevaluated especially wellby
the observation made by the German weather service, the Seewarte,
regarding the Westerlies (west-wind-drift), which was weak during the fist
part of autumn, but ceased before the end of the year. Instead,a stable highpressure
system existed overEurope
since December 1939, which
suppliedverycoldair from the northandfended offwarmmoistairfrom the
Atlantic(see
Fig. above and Fig.C4-5, p. 63).Todaythe
situation
is called "weatherblocking”. A
highpressurearea
forces the movementof
maritimecyclones (lows) into
a different direction. Theautumn of 1939resultedinthedevelopmentand
impact of theblockadeweather, which could not have been better
presented by nature to the scientific community for a thorough
investigation. It is asifa large trialhad
taken place.

Itwas apurelypracticallarge-scale trial, which ran in
Europe
since September 1st, 1939. Back then, when the trail commenced,
there wasnottheslightest hintthataweather blockade could develop over northernEurope during theautumnmonths.
That changedrapidly after
the war unlashed physical forcesofgigantic scale. Air and landactivitiesinterveneddirectlyinthe status of the atmosphere,
for example,when thousandsofaircraft left their
contrailsinthe skyor whenexcessiveburningvillagesand cities inPoland, moveddustandashinto the air, where
they could serve ascondensationnuclei
forrain that indeed came down massively in some
locations. Especially thosenaval activities from
the English Channelto the North Capeandthe
Gulf of Finlandwere likely toinfluence
the directionof low pressure areas. Thus
providing humidity forthecontinuous rainalong the
river Rhine,and turning theprevailingwinddirection
to the opposite,namely from the
south-west to the north-eastquadrant.These are allcriteria thathavecontributed to a
weather blockadingsituation
that eventually ruled the conditions during the first war winter.
It all was anthropogenic in originandshouldthereforebeinvestigated verymeticulously,
to be understood, and explained by climatescience.

Fig.
C5-11, Air pressure in mb over the North Atlantic and Europe on 31st
December 1939